Bacterial versus viral infections |
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Determination of SAA is today cumbersome because of lack of methods for routine measurements.The
routine methods for CRP are today mostly immunoturbidimetric or nephelometric. The introduction of the
international standard IFCC CRM 470 has made the available CRP assays very reliable.
CRP has proved useful in differentiating bacterial infections from viral infections. Bacterial infection
increases serum CRP concentration, whereas viral infection does not. The rise in CRP usually corresponds
to the extent of bacterial infection. Bacterial infections limited in scope may in some cases be
accompanied by normal or low CRP values. However, it may be that adeno-virus, as some herpes viruses, are
able to cause such massive tissue injury that CRP production is
triggered.
Among the most important qualities of CRP are its high sensitivity and high negative predictive value.
Measurement of CRP greatly facilitates the management of infectious diseases, and it can help to avoid
unnecessary use of antimicrobial agents in many patients with viral infections.
Determination of serum CRP is one of the few diagnostic tests that can be used at the early phase
of infection to reliably ascertain whether virus or bacteria is the causative agent and to decide
whether or not to start antibiotic therapy. Prescription of antibiotics in cases of viral infection
is pointless and carries the potential risk of generating antibiotic resistance in pathogenic
bacteria.
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